1. Field of the Invention
The present invention relates to a file management technique using a hierarchical structure of directories.
2. Description of the Related Art
Today's advanced computer technology has led to development of apparatuses for managing and searching files. Such apparatuses record various types of data files on a certain recording media, such as a magneto-optical disk (MO). One example of such an apparatus for searching image data files is an apparatus for searching medical image data files. As shown in FIG. 6, a typical medical image data file searching apparatus includes an operating section 1, a control section 2, a disk drive 3, an interface 4, and a display section 5. The operating section 1 is a keyboard or the like, from which a user enters information to the control section 2. In response to the instruction entered from the operating section 1, the control section 2 records a data file on a recording medium held in the disk drive 3.
The disk drive 3 writes and reads data to and from the recording medium, such as an MO, in response to instructions from the control section 2. The interface 4 may be, for example, one confirming to the RS-232 standard, and is connected to an external device, such as a CT (Computerized Tomography) apparatus. The display section 5 is a display apparatus or the like.
The control section 2 stores image data supplied from the external device via the interface 4 in the recording medium as an image data file in a predetermined format, and updates a management data file which describes the contents of each image data file. As shown in FIG. 7, the management data file consists of pieces of information identifying a particular image data file, such as a starting position of a record (e.g., a cluster ID) on the recording medium and a file name, together with associated information (management information) data including a patient identifier, an imaging date, and a test identifier.
During data recording, a user operates the operating section 1 to enter a patient identifier. In response, the control section 2 is placed in a recording standby state. When the recording button on the operating section 1 is depressed, the control section 2 allocates a test identifier to image data supplied via the interface 4, and outputs an instruction to the disk drive 3 to record the image data as an image data file. At the same time, the control section 2 associates the information identifying the image data file with the patient identifier entered by a user, current date (available from a clocking section which is not shown in the figure), and the allocated test identifier, and records this data in the management data file.
To view image data files, a user enters a particular patient identifier from the operating section 1. In response, the control section 2 looks up the management data file to search for the entered patient identifier, and creates a list of imaging dates associated with the patient identifier. The list is displayed on the display section 5 and, when the user specifies a particular imaging date, the control section 2 selects a matching imaging date from the retrieved list, and displays the image data files associated with the particular imaging date on the display section 5 in seriatim.
Alternatively, a user may select a desired data file according to the imaging date, rather than a patient identifier. In such a case, the user uses the operating section 1 to enter a particular imaging date. In response to this input, the control section 2 looks up the management data file, creates a list of image data files associated with the entered imaging date, and displays the list on the display section 5. When so instructed by the user, the image data files of the list may be displayed succeedingly.
In this type of searching apparatus, dedicated software is required because the apparatus uses the management data file. To facilitate viewing the image data on a personal computer, there has been developed an apparatus which creates a hierarchical structure of directories using a widely known file system used in personal computers to classify and manage the image data files.
FIG. 8 shows an example of such a hierarchy of directories used for classification and management of image data files. Herein, a root directory (¥) is created for accumulating image data files. Under the root directory, subdirectories are created for each patient identifier, under which subdirectories are created for each imaging date. Under the subdirectories of imaging date, other subdirectories are created for each test identifier, in each of which at least one image data file being stored.
To implement a searching method utilizing the hierarchical structure of directories, the control section 2 operates as follows during imaging. Specifically, when a particular patient identifier is entered from the operating section 1, the control section 2 checks if a directory corresponding to the entered patient identifier already exists. If such a directory is found, that directory is then searched for a directory corresponding to the current date (imaging date). If found, it is further checked in the current date directory for a directory corresponding to a test identifier allocated at the time of imaging. If found, then an image data file is stored in the test identifier directory. However, if no directory has been created for the patient identifier, the imaging date, or the test identifier, a corresponding directory is created and the image data files are stored therein.
In this method, if image data files are in a standard format, such as the JPEG (Joint Picture Expert Group) format, a desired image data file is retrieved on a personal computer by following the hierarchy of directories, that is, opening a directory of patient identifier corresponding to a desired image data file, a directory of a desired imaging date, and a directory of a desired test identifier.
In the searching method using the management data file, overall processing load may increase, because the size of the management data file becomes bigger as the recording medium has larger capacity. As a consequent, searching while viewing files requires a greater amount of time, or more space in a working memory is used while the control section 2 reads the management data file.
When managing and searching files in the hierarchical structure of directories, if it is desired to view a list of test identifiers, for example, those associated with a particular imaging date when searching directories corresponding to a desired patient identifier or imaging date, a recursive search is required. Specifically, a user must move a current working directory from the root directory to a patient identifier directory, and must then return to the root directory to restart the search for another patient identifier directory. As a result, when the recording medium has a large capacity, a substantial amount of time is required for searching and reading.